JPS5840028B2 - Ignition timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an automobile engine,
In particular, this relates to control of ignition timing depending on whether or not exhaust gas recirculation is performed.

In automobile engines, nitrogen oxides (N
It is known that exhaust gas is recirculated (hereinafter referred to as EGR) to the intake system in order to reduce E
When GR is performed, the combustion speed within the engine combustion chamber decreases, causing a deterioration of the combustion state and deterioration of fuel efficiency.

For this reason, it has been found that deterioration of the combustion state can be prevented by advancing the ignition timing by an appropriate amount when performing EGR.

That is, as shown in the characteristic diagram of fuel efficiency and NOx emission weight with respect to ignition timing in Fig. 1, when the EGR rate determined from the EGR amount and intake air amount is, for example, 10%, the ignition timing is set to 200 before top dead center (BTDC). It has been found that when the angle is advanced, the weight of NOx emissions can be reduced by approximately half compared to when the angle is advanced.

Note that curve A in FIG. 1 shows a constant fuel consumption rate curve.

The present invention has been made in view of this fact, and is based on a known type of EGR that uses engine intake negative pressure as a driving source to drive a diaphragm and open/close a valve to control whether or not to perform EGR.
A device equipped with a GR control valve includes a valve opening detection means for detecting whether an exhaust gas recirculation control valve (EGR control valve) is opened, and the EGR control valve is opened by the valve opening detection means. When the EGR control valve is opened, the ignition timing is stepped by a predetermined crank angle when a predetermined time corresponding to the delay time from this point until the exhaust gas is recirculated into the cylinders of the engine has elapsed. By having a configuration that advances the ignition timing in steps, it is possible to prevent the engine combustion condition from deteriorating when EGR is performed, and to advance the ignition timing after confirming whether EGR is actually being performed. This prevents malfunctions such as advancing the ignition timing when EGR is not being performed, and also prevents knocking by advancing the ignition timing immediately after the EGR control valve opens and EGR gas is recirculated to the intake system. An object of the present invention is to provide an ignition timing control device that can prevent problems such as the occurrence of ignition timing and shorten the time period for which combustion conditions deteriorate immediately after exhaust gas recirculation.

FIG. 5 is an overall configuration diagram for clearly showing the configuration of the present invention.

The EGR control valve 13 has a diaphragm 1-driven valve that uses the engine's intake negative pressure as a driving source, and is configured to switch the EGR control state.
This detects whether or not the R control valve is opened.

Further, the valve opening/closing determination means determines that the EGR control valve is opened upon receiving a signal from the valve opening degree detection means, and the time measurement means measures the elapsed time from the time when the EGR control valve was opened. .

The elapsed time determining means determines whether the measured time has exceeded a predetermined time period corresponding to a delay time from when the EGR control valve is opened until the exhaust gas is recirculated into the cylinders of the engine. When the value exceeds the value, the ignition timing correction means advances the ignition timing of the engine by a predetermined value set by the EGR advance value setting means.

The ignition means controls the ignition timing so that ignition is performed at the ignition timing corrected by the ignition timing correction means.

The present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 2 is a configuration diagram of an engine equipped with the device of the present invention,
In the figure, 1 is the engine body, 2 is the intake pipe provided with the throttle valve 5, 3 is the surge tank downstream of the throttle valve 5,
4 is an exhaust manifold.

6 is a throttle sensor that detects the opening degree of the throttle valve 5, and an idle switch 6a that detects the idle opening degree of the throttle valve 5, that is, the fully closed state, and the full throttle opening degree, that is, the fully open state (about 55 degrees or more) of the throttle valve 5. It consists of a fully open switch 6b that detects.

T is a water temperature sensor that detects the engine cooling water temperature, 8 is an intake air amount sensor that detects the intake air amount of the engine, and this intake air amount sensor 8 has a built-in intake air temperature sensor 9 that detects the temperature of the intake air. .

10 is an ignition coil forming part of the engine ignition system; 11
is a distributor that distributes the ignition energy of the ignition coil 10 to the spark plugs installed in each cylinder of the engine.

As is well known, the distributor 7 is rotated once by two revolutions of the engine's crankshaft, and is provided with a rotation angle sensor 12 for detecting the engine rotation angle.

The rotation angle sensor 12 includes a reference angle sensor 12a that outputs a signal at a predetermined crank angle only once every two rotations of the crankshaft for detecting the reference position of the crank angle, and an angle sensor that outputs a signal at every predetermined crank angle. 12b.

13 is an exhaust gas recirculation control valve (EGR control valve) that recirculates exhaust gas from the exhaust manifold 4 to the upstream side of the throttle valve 5 of the intake pipe 2, and is connected to the exhaust manifold 4 and the intake pipe 2 via pipes 13a and 13b. It is connected.

This EGR control valve 13 is connected to a valve 13d for opening and closing the exhaust gas passage 13c, and the other end of this valve 13d is connected to the valve 13d.
It has a known configuration consisting of a diaphragm 13e that displaces the diaphragm 13e, a case 13f that forms a negative pressure chamber 13g between the diaphragm 13e, and a spring 13h that applies a load to the diaphragm 13e in the direction of closing the valve 13d.

Reference numeral 14 denotes an electromagnetically actuated negative pressure switching valve having a known configuration, which is connected to the surge tank 3 via a pipe 14a, and at the same time to the negative pressure chamber 13g of the EGR control valve 13 via a pipe 14b. The pressure introduced into the negative pressure chamber 13g of the surge tank 73 is controlled to be switched between the intake negative pressure in the surge tank 73 and the atmospheric pressure.

A negative pressure detection switch 15 is installed on the pipe 14b and serves as a valve opening detection means for detecting whether negative pressure is introduced into the EGR control valve 13, that is, whether the EGR control valve 13 is opened.

The negative pressure detection switch 15 is integrally connected to a diaphragm 15b forming a negative pressure chamber 15a into which the pressure in the pipe 14b is introduced, a spring 15c installed in the negative pressure chamber 15a and urging the diaphragm 15b, and the diaphragm 15b. The movable contact 15d is electrically insulated and fixed to the housing 15e, and the movable contact 15d is grounded to the body via a spring 15c.

Reference numeral 16 denotes a microcomputer forming a control circuit for controlling the opening period and ignition timing of the EGR control valve 13.

Next, the microcomputer 16 will be explained in detail with reference to the block diagram shown in FIG.

100 is a microprocessor unit that calculates the opening period and ignition timing of the EGR control valve 13, and also includes a clock signal generation circuit.

Reference numeral 101 denotes an interrupt command unit that commands the microprocessor unit 100 to perform interrupt processing for calculation of ignition timing based on reference angle signals from both sensors 12a and 12b of the rotation angle sensor 12 built into the distributor 11, and is transmitted through the common bus 123. microprocessor unit 100
A signal is transmitted to

Further, the interrupt command unit 101 outputs a signal for controlling the operation start timing of a unit described later.

Reference numeral 102 denotes a rotational speed counter which receives the rotational angle signal from the rotational angle sensor 12, counts the period of a predetermined rotational (crank) angle using a clock signal of a predetermined frequency from the microprocessor unit 100, and calculates the engine rotational speed from this. It is a unit.

Reference numeral 103 denotes an AD conversion processing unit including an analog multiplexer, which has a function of AD converting each signal from the intake air amount sensor 8, water temperature sensor 7, and intake temperature sensor 9, and sequentially reading the signals into the microprocessor unit 100.

Reference numeral 104 outputs signals from the idle switch 6a and full open switch 6b of the throttle sensor 6 as well as a signal from the negative pressure detection switch 15 to the microprocessor unit 104 according to a control signal from the microprocessor unit 100.
This is a digital signal processing unit that sequentially reads data into the 0s.

Information transmission between these units 102, 103, 104 and microprocessor unit 100 is performed through common bus 123.

105 stores a control program for the microprocessor unit 100, and each unit 101, 102,
A memory unit having a function of storing output information from the microprocessor unit 103 and 104.
Information transmission between the two is performed through the common bus 123.

106 is a counter unit for ignition timing control including a register, and an output (digital) signal representing the timing to energize the ignition coil 10 and the timing to cut off the energization calculated by the microprocessor unit 100, that is, the ignition timing, is sent to the interrupt command unit 101. Based on the angle signal from the ignition coil 10, the timing corresponding to the engine rotation (crank) angle is calculated, and a pulse signal having a time width for energizing the ignition coil 10 is output.

107 is an amplifier that amplifies the output of this counter unit 106 and drives the ignition coil 10.

108 receives a signal calculated by the microprocessor unit 100 indicating whether or not to perform EGR;
When a signal indicating that EGR should be performed is input,
This is a valve drive circuit that energizes and drives the negative pressure switching valve 14.

FIG. 4 shows a schematic flowchart of the microprocessor unit 100, and the functions of the microprocessor unit 100 will be explained based on this flowchart.

When the engine is started, the calculation of the main routine is started at the start of the first step 1001, and in the second step 1002, it is checked whether the full open switch 6b of the throttle sensor 6 is off, that is, the throttle valve 5 is not fully open. If the fully open switch 6b is off, the process advances to the third step 1003.

In the third step 1003, it is determined whether the idle switch 6a of the throttle sensor 6 is off, that is, whether the throttle valve 5 is fully closed. If the idle switch 6a is off, the process advances to a fourth step 1004.

In the fourth step 1004, the engine cooling water temperature tw is calculated based on the information representing the engine cooling water temperature tw from the water temperature sensor 7.
It is determined whether or not the temperature is higher than a predetermined temperature (for example, 40° C.), and if the temperature is higher than the predetermined temperature, the process proceeds to the fifth step 1005.

In the fifth step, it is determined whether or not the intake air temperature ta is higher than a predetermined temperature (for example, 15°C) based on the information representing the intake air temperature ta from the intake air temperature sensor 9.
Proceed to 06.

In a sixth step 1006, a signal for turning on the negative pressure switching valve 14, that is, a signal indicating that EGR should be performed, is supplied to the valve drive circuit 108.

When it is determined in the second step 1002 that the full open switch 6b is not off, and when it is determined in the third step 1003 that the idle switch 6a is not off, the fourth step 1
When it is determined in step 004 that the engine cooling water temperature tw is below the predetermined temperature, or when it is determined in the fifth step 1005 that the intake air temperature ta is below the predetermined temperature, the process proceeds to a seventh step 1007.

In the seventh step 1007, a signal to turn off the negative pressure switching valve 14 is supplied to the valve drive circuit 108.

After processing the sixth step 1006 or the seventh step 1007, the process proceeds to the eighth step 1008.
In step 008, it is determined whether the negative pressure detection switch 15 is turned on, that is, whether negative pressure is introduced into the EGR control valve 13 and EGR is actually performed. Proceed to.

In the ninth step 1009, it is determined whether or not the negative pressure detection switch 15 was off in the previous calculation cycle of this main routine. If the negative pressure detection switch 15 was off in the previous calculation cycle, the process proceeds to the tenth step. move on.

In a tenth step 1010, a process is started to measure the time from when the negative pressure detection switch 15 is turned off until a predetermined time (for example, 1 second) has elapsed.

If the negative pressure detection switch 15 was on in the previous calculation cycle in the ninth step 1009, the process goes to the eleventh step 1.
011, and from the tenth step 1010, the first step
1 step 1011, and in the 11th step, it is determined whether a predetermined time (for example, 1 second) has elapsed (ie, measured) since the negative pressure detection switch 15 was turned off, and when the predetermined time has elapsed, the The process proceeds to step 1012, and if the predetermined time has not elapsed, the process proceeds to a thirteenth step 1013.

In the tenth step 1010, the ignition timing is set by 5 in crank angle.
°Support for progress.

When it is determined in the eighth step 1008 that the negative pressure detection switch is not on, that is, EGR is not being performed, the process also proceeds to the thirteenth step 1013;
Therefore, I support not correcting the ignition timing using EGR.

From the 12th step 1012 and the 13th step 1013, the process advances to the 14th step 1014.
In step 14, a correction advance amount of the ignition timing is calculated according to the engine cooling water temperature tw and the engine state such as when the engine is under high load, and the process proceeds to step 15.

In the 15th step 1015, the calculation of the main routine is finished, and the calculation process of the main routine is started again from the second step 1002 at a predetermined cycle (for example, 51°2m5ec).
Have them do this repeatedly.

8th step 1008 to 14th step of the above main routine
The calculations up to step 1014 are performed by advancing the ignition timing by 5 degrees of crank angle after a predetermined time (1 second in this embodiment) has elapsed since the EGR control valve 13 was opened by the negative pressure detection switch 15, and in other cases. This prevents the ignition timing from being corrected by EGR.

By performing this calculation process, there is a predetermined time delay from when the EGR control valve 13 is opened until the exhaust gas is actually recirculated into the engine cylinder via the intake pipe 2 of the engine, so the ignition timing will advance. The instability of engine combustion can be resolved by delaying the angle correction by a time corresponding to this delay.

The interrupt command unit 101 forms a signal for issuing an interrupt command for ignition timing calculation based on the reference angle signal and the angle signal from both sensors 12a and 12b of the rotation angle sensor 12, and supplies it to the microprocessor unit 100. .

This interrupt command signal is transmitted to the microprocessor unit 100.
When the microprocessor unit 100 interrupts the arithmetic processing of the main routine and starts the interrupt arithmetic operation of the interrupt handling routine shown as the 20th step 1020, as shown in FIG. The engine rotation speed information N obtained by the rotation speed counter unit 102 is taken in.

Next, in the 22nd step 1022, the intake air amount sensor 8
- Intake air amount information Q obtained via the D conversion processing unit 103.

Next, in a 23rd step 1023, the basic ignition timing, that is, the basic advance amount is calculated from the image information N and Q.

Next, in the 24th step 1024, the first
Based on the calculation information of the correction advance amount of the ignition timing obtained in step 1014, this basic advance amount is corrected and calculated.

Next, in a twenty-fifth step 1025, information representing the corrected and calculated advance angle amount is set in the ignition timing control counter unit.

Next, at a twenty-sixth step 1026, the main routine returns to the interrupted arithmetic processing step.

Next, the main operations of the above-mentioned constituent device will be explained.

When the engine is running, the throttle sensor 6
Based on the signals from the water temperature sensor 7 and the intake temperature sensor 9, the microprocessor unit 100 determines whether EGR should be performed or not, and when the engine condition is such that EGR should be performed, a signal indicating this is output to the valve drive circuit 108. The electromagnetic coil of the negative pressure switching valve 14 is energized and the negative pressure is amplified.
It is supplied to the negative pressure chamber 13g of the GR control valve 13, and the valve 13d is opened.

As a result, exhaust gas is introduced from the exhaust manifold 4 into the intake pipe 2 and supplied into the engine cylinder chamber, thereby lowering the combustion temperature within the cylinder chamber and suppressing the generation of NOx.

When the microprocessor unit 100 determines that EGR should be stopped, the current supply to the negative pressure switching valve 14 is cut off, and the valve 13d of the EGR control valve 13 is closed to stop EGR.

On the other hand, regarding the ignition timing, the interrupt command unit 101
Every time an interrupt command is issued, the microprocessor unit 100 calculates the ignition timing and outputs information representing the ignition timing to the ignition timing control counter unit 106.

The counter unit 106 uses this information to measure the crank angle corresponding to the timing at which the ignition should be ignited, based on a signal synchronized with the crank angle from the interrupt command unit 101.

The output of this counter unit 106 is amplified by an amplifier 107 and energized to the ignition coil 10, and the energization is cut off at a crank angle corresponding to the ignition timing, and the high voltage generated in the secondary coil of the ignition coil 10 is passed through the distributor 11. Supplied to the spark plug of the corresponding cylinder.

As described in the explanation of the schematic flowchart of the microprocessor unit 100 in FIG. 4, when EGR is performed, this ignition timing is advanced by a predetermined angle (in this embodiment, crank angle 5°), and EGR is performed. It is possible to prevent deterioration of the combustion state due to this.

As described above, the ignition timing control device of the present invention includes an exhaust gas recirculation control valve that uses engine intake negative pressure as a driving source to drive a diaphragm to open and close the valve to switch the exhaust gas recirculation state, and the exhaust gas recirculation control valve. Valve opening degree detection means detects the open/closed state of the circulation control valve, and when a signal from this valve opening degree detection means is input and the exhaust gas recirculation control valve is opened, from this point on, the exhaust gas is not allowed to flow into the cylinders of the engine. and a control circuit that advances the ignition timing step by step by a predetermined value when a predetermined time corresponding to the delay time until the exhaust gas is recirculated has elapsed from the time when the exhaust gas recirculation valve is opened. When exhaust gas recirculation is performed, the ignition timing can be advanced in stages immediately after the recirculation has been performed, so the combustion condition of the engine is hardly deteriorated, and the exhaust gas is If there is a failure in the drive system of the gas recirculation control valve, it is possible to advance the ignition timing when exhaust gas recirculation is not occurring because it is possible to advance the ignition timing after confirming whether exhaust gas recirculation has actually occurred. It is possible to reliably prevent erroneous movements such as angular movement, and since the ignition timing is advanced after exhaust gas recirculation control has started, it has the excellent effect of preventing problems such as knocking. .

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram for explaining the present invention in detail, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a block diagram of the microcomputer shown in FIG. 2, and FIG. FIG. 3 is a schematic flowchart of the microprocessor unit, and FIG. 5 is an overall configuration diagram for clearly showing the configuration of the present invention. 13... Exhaust gas recirculation 1 (EGR) control valve, 1
5... Negative pressure detection switch forming valve opening detection means, 16... Microcomputer forming control circuit.

Claims (1)

[Claims] 1 An exhaust gas recirculation control valve that uses the engine's intake negative pressure as a driving source to drive a diaphragm to open and close the valve to switch the exhaust gas recirculation state, and a valve opening that detects the open/closed state of the exhaust gas recirculation control valve. a valve opening/closing determination means for determining whether the exhaust gas recirculation control valve is opened or closed based on an output signal of the valve opening detection means; a time measuring means for measuring the passage of time from a point in time, and the measured time corresponds to a delay time from the time when the exhaust gas recirculation control valve is opened until the exhaust gas is recirculated into the cylinders of the engine. elapsed time determining means for determining whether or not a predetermined time has elapsed; and when the elapsed time exceeds the predetermined time, the ignition timing of the engine is adjusted by a predetermined value set by the exhaust gas recirculation advance value setting means. An ignition timing control device comprising: ignition timing correction means that advances the ignition timing in stages; and ignition means that controls ignition timing according to the correction result of the ignition timing correction means.